Where can i get one of those for us$40?
Flea-bay, like all the other bargains. Maybe not $40, but not much more and you get much more bang for your buck
The effort is a laugh: about 1 optocoupler and 2 resistors.
Maybe, but at £3.45 from http://www.cohaku.com/item/usb.....-vista-mac
, it isn't worth the bother or the coding (and you forgot about the wiring and the connectors.
And why would a mountaineer want to climb that mountain – someone else has already gone up it…
The RPi is all about the pursuit of new knowledge and experiences, this can be worth far more than something being easy.
Also I imagine there would be ways to get the GPU to perform some very powerful operations giving you extreme amounts of bang for your buck - if your maths and coding skills are up to it.